My fireplace has a metal flu plate that lays against a metal frame The frame does not meet the chimney wall There is a gap of over 1/2" letting in plenty of cold air I was thinking of filling the gap with rutland mortar mix or similar insulating mortar I would wire a 32" angle bracket to the frame to keep mortar from slumping, then fill in the gap as shown in this picture
..................||.<Chimney.wall
..................||
frame.V.oooo||
......----OOO||
...../.....oooo||....the.oooo.are.beads.of.mortar.to.fill.1/2".gap.
..../......----.||
.../.......!.....
../........!.<=temp.angle wired to frame keeping mortar from slumping
./.........!
/...<<<<<.flu.plate
But, rutland mortar says it is to be applied 1/8" at a time with heat curing in between layers
What should I use instead?
..................||.<Chimney.wall
..................||
frame.V.oooo||
......----OOO||
...../.....oooo||....the.oooo.are.beads.of.mortar.to.fill.1/2".gap.
..../......----.||
.../.......!.....
../........!.<=temp.angle wired to frame keeping mortar from slumping
./.........!
/...<<<<<.flu.plate
But, rutland mortar says it is to be applied 1/8" at a time with heat curing in between layers
What should I use instead?